P70, P72, and P170 Series Controls for Low Pressure Applications Installation Instructions
8
Checkout Procedure for Low Pressure Cut-out
Controls
Use the following procedure to check control operation
on a typical low pressure cut-out application.
1.
Check the product label on the inside of the control
cover, for model number and switch action. (See
Table 5 for low and high events that correspond to
control model and switch action.)
2.
Attach a reliable gauge to the suction service port
and run the system at normal conditions.
3.
Slowly front seat the suction valve and allow the
low side to pump down. Observe the control’s low
event switching pressure on the gauge.
4.
Slowly back the suction valve off the front-seated
position and allow the low side pressure to rise.
Observe the control’s high event switching
pressure on the gauge.
5.
Adjust settings as needed. (See Figure 8.) Repeat
checkout procedure if necessary.
Manual Reset Operation
Pressure controls with the Manual Reset option lock
out when they reach Cutout pressure and must be
manually reset by the user to restart the controlled
equipment. The manual reset mechanism is trip-free
and cannot be overridden by blocking or tying the reset
button down.
On equipment with locked out controls, first determine
and remedy the cause of the lockout, and allow the
sensed pressure to return to the Cut In setpoint. Then,
press and release the reset button on the front of the
control to restore operation of the controlled
equipment.
IMPORTANT:
Use the pressure control settings
recommended by the manufacturer of the controlled
equipment. Do not exceed the pressure ratings of
the controlled equipment or any of its components
when checking pressure control operation or
operating the controlled equipment.
IMPORTANT:
After mounting, wiring, and
evacuating the control, attach a reliable set of
gauges to the controlled equipment, and operate the
equipment (at least) three cycles at the pressures
necessary to verify control setpoints and proper
equipment operation.
